In recent years, it has become more and more popular to distribute media content (hereinafter, simply referred to as “content”) over digital networks. As defined herein, “content” has characteristics such that it varies over time from its beginning to end, as in an audio or video (moving picture) content. As such, content has a large data size relative to that of a still image or text. Typically, content is transmitted over a digital network from a device which is on the distributing end of the content (hereinafter a “distributing apparatus”) to a device which is on the receiving end of the content (hereinafter a “recipient apparatus”) by using either a streaming technique or a downloading technique, depending on the purpose for which the content is used (as described later).
Streaming is a technique in which a recipient apparatus that is acquiring the content from a distributing apparatus over a digital network is allowed to reproduce the acquired content during the acquisition. In other words, streaming is mainly directed to on-line reproduction of contents by the recipient apparatus. More specifically, the distributing apparatus splits the content into a number of data blocks, and sequentially delivers the generated data blocks to the recipient apparatus. In the recipient apparatus, each received data block is buffered to memory, and thereafter reproduced. Each data block which has been reproduced is discarded. The recipient apparatus may include in its interior a non-volatile storage device such as a hard disk drive, but the data blocks are not meant to be stored in such a non-volatile storage device under most streaming techniques. Thus, under most streaming techniques, copies of content are not generated on the internal storage device of the recipient apparatus. As such, streaming techniques are likely to be employed for the distribution of content which have a relatively short reproduction time and/or a relatively low quality, e.g., music samples, video digests, or movie previews.
On the other hand, downloading is a technique in which the recipient apparatus first acquires the entire content from the distributing apparatus, saves the content, and thereafter reproduces the saved content. In other words, downloading is mainly directed to off-line reproduction of content by the recipient apparatus. More specifically, the recipient apparatus saves the content which has been obtained from the distributing apparatus to a non-volatile storage device in the recipient apparatus. Thereafter, in response to a user's instructions, the recipient apparatus reproduces the saved content. Thus, in a downloading technique, a copy of the content is generated within the recipient apparatus, unlike in a streaming technique. As such, downloading techniques are likely to be employed for the distribution of content which has a relatively long reproduction time and/or a relatively high quality, e.g., complete pieces of music or video, or actual movies themselves.
As described above, streaming and downloading have different characteristics. There is conventional content distribution systems which utilize such different characteristics of the two types of techniques in such a manner that the distribution of content is performed while switching between streaming and downloading, depending on the content is being transmitted. In such a conventional content distribution system, streaming is initially employed, immediately after a content distribution is begun. During streaming, the recipient apparatus will begin reproducing a content every time a certain number of data blocks therefrom have been accumulated and therefore the user can begin to enjoy the content after a relatively short wait time. On the other hand, if the transmission error rate increases after the content distribution has begun, the distributing apparatus switches its operation from streaming to downloading. Since a downloading technique is of such a nature that it allows for an easier error correction than a streaming technique, the aforementioned switching from streaming to downloading can prevent degradation in the content quality. Also, if the transmission band width becomes scarce during downloading, those contents which can suitably be distributed through multi-casting will be distributed through multi-casting by switching to streaming.
During a content distribution in general, a user who has acquired a content by means of his or her recipient apparatus and is currently enjoying the acquired content on the recipient apparatus may wish to save the currently-reproduced content, in its entirety, in the recipient apparatus. However, since a conventional contents distribution system employs streaming immediately after beginning a content distribution, those portions of the content which have already been reproduced are discarded. Therefore, even if the user decides to save the entire content in the recipient apparatus in the aforementioned situation, the distributing apparatus will need to redeliver the entire desired content through downloading, from beginning to end; and the recipient apparatus will then save in an internal non-volatile storage device the whole content thus delivered. Thus, in accordance with a conventional contents distribution system, at least the beginning portion of a content needs to be delivered twice, thereby hindering efficient content distribution.
The aforementioned problem will be more specifically described. Generally speaking, a user who is thinking of purchasing a piece of music as content may wish to try a sample of the music prior to making the purchase. Similarly, a user who is thinking of purchasing a complete body of video or an actual movie as content may wish to try a previously-prepared sample version of the video prior to the purchase (e.g., a video digest or a movie preview). In order to enjoy such a partial content, the user issues an instruction in accordance with a the recipient apparatus that requests the distributing apparatus to distribute the partial content. Thereafter, the recipient apparatus reproduces the partial content sent from the distributing apparatus in the streaming mode. After reproduction is over, the partial content is discarded by the recipient apparatus.
After the partial content has been enjoyed, depending on the user's decision, the recipient apparatus may request the distributing apparatus for the complete, entire content (e.g., the whole music or video). In conventional content distribution systems, in response to a request from the recipient apparatus, the distributing apparatus delivers the complete music or video as content to the recipient apparatus; while switching between streaming and downloading as appropriate.
It is often the case that a complete piece of music (or video) and a music (or video) sample therefor contain the same substance. However, conventional content distribution systems work in such a manner that, after the user has enjoyed partial content (e.g., a music sample, a video digest, or a movie preview), the recipient apparatus receives the complete content in its entirety. Thus, it takes a substantial amount of time for the recipient apparatus to save the complete content. Furthermore, the user cannot enjoy the complete content until the downloading process is completed at the recipient apparatus. In this respect, the conventional content distribution systems are not performing an efficient content distribution on behalf of the user.
In recent years, as another type of recipient apparatus, recording apparatuses (i.e., apparatuses that internalize any of a variety of recording media, e.g., a HD (Hard Disc), a DVD (Digital Versatile Disc) or a Blu-Ray® disc) have been made into products. Such a recording apparatus is connected to a display device, e.g., a television set, in most cases. A user who has been viewing a content (e.g., a video program) which is displayed on the display device up to a certain point may wish to save the content to the recording apparatus. However, as described above, the conventional content distribution systems discard those portions of the content which have already been reproduced. Therefore, a user wishing to save the entire content to the recording apparatus in the aforementioned situation will need to wait for a rerun of the same program in future. This case is another example which illustrates the need to deliver the same content twice.
Thus, an object of the present invention is to provide a contents distribution system which makes possible an efficient content distribution.